WARSAW, May 31 - A NATO summit set for Warsaw in July comes at a "critical time" as the alliance deals with Russian assertiveness and the threat of terrorism amid other challenges, Secretary-General Jens Stoltenberg said Tuesday, AP reported.

Stoltenberg was speaking following talks with Poland's Defense Minister Antoni Macierewicz, who said that four battalions are to be stationed in Poland and in the three Baltic states, giving the region a greater sense of security. A battalion typically has between 300 and 800 troops.